present value

Calculate the present value for each section using compound interest. A) You need $1,000 in 8 years. You can invest your money at 3%/a compounded semiannually.
B) You need $200 in 30 months. You can invest your money at 6%/a compounded monthly.
C) You need $15,000 in 12.5 years. You can invest your money at 4%/a compounded quarterly.